Line-commutated rectifiers (LCRs) are extensively utilized in exciters of large electrical machines, ac-dc power systems of ships, vehicles, aircraft, and many other industrial applications. Efficient and accurate computer simulations are necessary to analyze various aspects of such systems under both normal and unbalanced/faulty operating conditions. The so-called parametric average-value modeling (PAVM) technique has been recently developed and shown to provide accurate and computationally efficient models of power-electronic converters for system-level simulations. In this paper, the PAVM methodology is extended to LCRs with internal faults. The new formulation considers the asymmetrical operation of rectifiers by including the ac-side characteristic (i.e., 5th, 7th, etc.) and non-characteristic (i.e., 2nd, 3rd, 4th, etc.) harmonics in both positive and negative sequences as well as dc components that may be present on ac variables. The proposed PAVM is verified by experimental measurements and detailed model and is demonstrated to have excellent accuracy under various operating modes and fault configurations.